Lighting device

ABSTRACT

A lighting device includes a substrate and a planar light source portion including a plurality of LED chips arrayed on the substrate. The planar light source portion faces an illumination space (space to be illuminated) by a predetermined opening area. The plurality of LED chips are arrayed on the substrate such that the mounting density with respect to the opening area is not less than 3/cm 2 , and accordingly, a planar light source is formed.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 15/054,093, filed onFeb. 25, 2016, which is a continuation of U.S. application Ser. No.14/568,935, filed on Dec. 12, 2014, now U.S. Pat. No. 9,303,833, whichis a continuation of U.S. application Ser. No. 13/058,822, filed on Feb.11, 2011, now U.S. Pat. No. 8,915,610, which is a national phase ofinternational application PCT/JP2009/003838, filed on Aug. 10, 2009.Furthermore, this application claims the benefit of foreign priority ofJapanese application 2008-206865, filed on Aug. 11, 2008, Japaneseapplication 2008-317048, filed on Dec. 12, 2008, Japanese application2008-324837, filed on Dec. 22, 2008, Japanese application 2009-003727,filed on Jan. 9, 2009, and Japanese application 2009-108334, filed onApr. 27, 2009. The disclosures of these earlier Japanese, international,and US applications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a lighting device using light-emittingdiodes (hereinafter, referred to as LEDs) as a light source. Thislighting device may be mounted on, for example, a ceiling of a building,and used as a so-called downlight which performs downward illuminationto a floor surface, etc. Also, this lighting device may have a form ofan LED lamp which can be used as an alternative to the fluorescent lamp.

BACKGROUND ART

A downlight is a lighting device which is mounted in advance on aceiling, etc., of a building, and is used to create, for example, a warmatmosphere by illuminating a floor or a table, etc. (for example, referto Patent document 1). A conventional lighting device to be used for adownlight includes, for example, a halogen lamp as a light source. Ahalogen lamp is a so-called point light source which emits light invarious directions. In order to direct light from the halogen lamptoward a desired range, the lighting device is provided with acone-shaped reflector.

However, a halogen lamp emits light by supplying electricity to afilament as a resistor and generates a large amount of heat along withluminescence. Therefore, as compared with a fluorescent lamp, forexample, the energy efficiency is inferior.

In order to direct light emitted in various directions from the halogenlamp toward a desired direction, the reflector inevitably has acomparatively large shape which is parabolic in a cross section, forexample. Therefore, to attach the lighting device, a corresponding spacemust be secured on the ceiling.

FIG. 48 is a sectional view showing an example of a conventional LEDlamp which can be used as an alternative to a fluorescent lamp (forexample, refer to Patent Document 1). The LED lamp X1 shown in thisdrawing includes a long rectangular substrate 191, a plurality of LEDmodules 192 mounted on the substrate 191, a heat radiation member 195 towhich the substrate 191 is attached, a case 193 housing the substrate191, and terminals 194. On the substrate 191, a wiring pattern not shownto be connected to the plurality of LED modules 192 and the terminals194 is formed. The LED lamp X1 is arranged to make a plurality of LEDmodules 192 emit light by fitting the terminals 194 into slots ofsockets of a general fluorescent lamp lighting fixture.

However, in the LED lamp X1, when it is turned on, individual LEDmodules 192 look like point light sources. Therefore, in order to makethe appearance of the LED lamp X1 look like a fluorescent lamp, it isnecessary to greatly diffuse light from the LED modules 192 by the case193. As the diffusion effect by the case 193 increases, thetransmittance of the case 193 decreases. This deteriorates the luminousefficiency of the LED lamp X1.

If the current to be supplied to each LED module 192 is increased toincrease the luminance of the whole LED lamp X1, heat generation fromthe LED modules 192 improperly increases. This also deteriorates theluminous efficiency of the LED lamp X1.

PRIOR ART DOCUMENT Patent Documents

Patent Document 1: Japanese Unexamined Patent Application PublicationNo. 2008-016417

Patent Document 2: Japanese Unexamined Utility Model ApplicationPublication No. H06-54103

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide a lighting deviceexcellent in energy efficiency.

A detailed object of the present invention is to provide a lightingdevice which is excellent in energy efficiency and can realizespace-saving.

Another detailed object of the present invention is to provide alighting device in the form of an LED lamp which emits light withuniform luminance and can increase the luminous efficiency.

Means for Solving the Problem

A lighting device to be provided according to a first aspect of thepresent invention includes a substrate and a planar light source portionincluding a plurality of LED chips arrayed on the substrate. In detail,the planar light source portion faces an illumination space (space to beilluminated) by a predetermined opening area. The plurality of LED chipsare arrayed (preferably, arrayed uniformly) on the substrate such thatthe mounting density of the LED chips with respect to the opening areabecomes not less than 3/cm², and accordingly, a planar light source isformed. The opening area may be larger than the area of the substratefacing the illumination space. Specifically, the planar light sourceportion may face the illumination space by an opening area larger thanthe area of the substrate. The opening area may be an area of thesubstrate surface facing the illumination space. Specifically, theopening area facing the illumination space of the planar light sourceportion may be equal to the area of the substrate surface. In this case,when only a partial region of the substrate surface faces theillumination space, the area of the partial region is the opening area,and when the entire region of the substrate surface faces theillumination space, the area of the entire region is the opening area.

With this configuration, by arraying a plurality of LED chips at a highdensity on the substrate, a planar light source portion is formed.Therefore, as compared with a case where several high-luminance LEDs areused, the drive current per one chip can be reduced, so that the LEDchips can be made to emit light in a current region with high energyefficiency. Therefore, a lighting device excellent in luminousefficiency can be realized. Also, a substantially planar light sourcecan be formed by a high-density array of the LED chips, so thatluminescence with a uniform luminance is realized. Further, the drivecurrent per one chip is small, so that the heat generation amount can bereduced. Therefore, a measure for heat radiation can be easily taken,and accordingly, the configuration of the lighting device can besimplified and downsized.

Further, light emitted from the planar light source portion advancesmainly in the normal direction of the surface of the substrate, and doesnot advance in various directions. Therefore, for example, as comparedwith a lighting device having a point light source such as a halogenlamp, a member for directing light toward a desired range, that is, forexample, a reflector can be made smaller. Therefore, the lighting devicecan be downsized, and when attaching the lighting device, a mountingspace on a ceiling can be made smaller.

A drive current per one chip of the plurality of LED chips is preferablynot more than 40% (more preferably, not more than 20%) of the ratedcurrent of the chip. More specifically, the drive current per one chipof the plurality of LED chips is preferably a value within the range of20±3% of the rated current of the chip. Still more specifically, thedrive current per one chip of the plurality of LED chips may be not morethan 8 mA (more preferably, not more than 4 mA).

In this drive current range, the LED chips have excellent luminousefficiency, so that a planar light source with excellent energyefficiency can be provided, and accordingly, a lighting device withexcellent luminous efficiency can be realized.

When the drive current per one LED chip is high, the luminance of eachLED chip increases and may cause illuminance unevenness. In detail, ashading pattern like stripes may be formed on the surface of an object(for example, a wall surface) at a short distance from the lightingdevice. On the other hand, when the drive current per one chip isdesigned within the above-described range, the illuminance unevennesscan be effectively reduced. Specifically, improvement in luminousefficiency and reduction in illuminance unevenness can be realizedconcurrently.

According to a preferred embodiment of the present invention, theplurality of LED chips belong to a plurality of groups connected inseries to each other, and the plurality of LED chips belonging to eachgroup are connected in parallel to each other. This configuration issuitable for making the LED chips emit light with high luminousefficiency.

In detail, the lighting device may further include a constant currentpower supply which supplies a current to the plurality of LED chips, andthe plurality of groups may be connected in series to the constantcurrent power supply. Accordingly, the current supplied from theconstant current power supply is distributed to the plurality of LEDchips connected in parallel in each group. Therefore, the drive currentof each LED chip corresponds to the number of LED chips (connected inparallel) constituting each group.

Specifically, the number of LED chips (connected in parallel) in eachgroup is preferably selected so that the drive current per one LED chipbecomes not more than 40% (preferably, not more than 20%) of the ratedcurrent of this chip. More specifically, the number of LED chips(connected in parallel) in each group is preferably selected so that thedrive current per one LED chip falls within a range of 20%±3% of therated current of this chip. The number of LED chips (connected inparallel) in each group may be selected so that the drive current perone LED chip becomes not more than 8 mA (more specifically, not morethan 4 mA).

According to a preferred embodiment of the present invention, thelighting device includes a plurality of LED modules each of whichincludes one or more of the LED chips and a pair of mounting terminalsspaced from each other.

In this case, the occupied area ratio of the plurality of LED modules tothe opening area is preferably not less than 20%.

According to a preferred embodiment of the present invention, each ofthe plurality of LED modules is disposed in a posture in which the pairof mounting terminals are spaced from each other in a first direction,and the plurality of LED modules are arrayed so as to form a pluralityof rows disposed parallel to each other along a second directionperpendicular to the first direction. This configuration is advantageousfor realizing uniform surface luminescence.

According to a preferred embodiment of the present invention, theplurality of LED modules are arrayed zigzag. This configuration ispreferable for realizing uniform surface luminescence.

According to a preferred embodiment of the present invention, a wiringpattern is formed on the substrate. The wiring pattern includes aplurality of pad portions each of which extends in the second directionand includes an anode linear portion and a cathode linear portiondisposed parallel and spaced from each other in the first direction, andan oblique joint portion which joins the anode linear portion of one ofa pair of the pad portions and the cathode linear portion of the otherof the pair of the pad portions. The pair of the pad portions areadjacent to each other in the second direction, and the anode linearportions and the cathode linear portions of the pair of the pad portionsare disposed on the same sides in the first direction. The plurality ofLED modules are mounted across the anode linear portions and the cathodelinear portions.

With this configuration, the LED modules arrayed systematically in thesecond direction can be connected so as to belong to a plurality ofgroups connected in series to each other. Systematic array of theplurality of LED modules is important for obtaining uniform surfaceluminescence. Connection of the plurality of LED modules so that the LEDmodules belong to a plurality of groups connected in series to eachother is advantageous for setting the current to be supplied to each LEDmodule to a low current suitable for high-efficiency luminescence.

According to a preferred embodiment of the present invention, the wiringpattern includes anode folding portions which join the anode linearportions adjacent to each other in the first direction, and cathodefolding portions which join the cathode linear portions adjacent to eachother in the first direction.

According to a preferred embodiment of the present invention, the wiringpattern further includes a straight joint portion which joins the anodelinear portion of one of a pair of the pad portions and the cathodelinear portion of the other of the pair of the pad portions. The pair ofthe pad portions are adjacent to each other in the second direction, andthe anode linear portions and the cathode linear portions of the pair ofthe pad portions are disposed on the sides opposite to each other in thefirst direction.

According to a preferred embodiment of the present invention, thelighting device further includes an anode electrode and a cathodeelectrode disposed close to one side in the second direction withrespect to the plurality of pad portions. With this configuration, theanode folding portions and the cathode folding portions can be disposedto face the anode electrode and the cathode electrode. This ispreferable for shortening the lengths of portions connecting the anodefolding portion and the cathode folding portion to the anode electrodeand the cathode electrode.

According to a preferred embodiment of the present invention, thecathode linear portions or the anode linear portions have widthsoverlapping the LED chips of the LED modules in a plan view. Thisconfiguration is suitable for radiating heat generated from the LED chipvia the cathode linear portion or the anode linear portion.

According to a preferred embodiment of the present invention, the wiringpattern includes at least one of an anode widened portion and a cathodewidened portion disposed close to an end portion of the substrate andhaving an external shape along an end edge of the substrate. Thisconfiguration is suitable for radiating heat generated from the LED chipvia at least one of the anode widened portion and the cathode widenedportion.

According to a preferred embodiment of the present invention, the wiringpattern includes a nonconductive radiation portion which is electricallynonconductive to the anode linear portions and the cathode linearportions, and positioned close to an end portion of the substrate withrespect to the anode linear portions and the cathode linear portions.This configuration is suitable for increasing heat radiation performancefrom the substrate.

According to a preferred embodiment of the present invention, thesubstrate is circular, and the lighting device further includes areflector which is formed to widen toward the end in the normaldirection of the surface of the substrate on which the plurality of LEDchips are mounted, and surrounds the planar light source portion, and asubstrate-side opening diameter D1 on the substrate side of thereflector and an exit-side opening and the exit-side opening diameter D2on the side opposite to the substrate of the reflector are set tosatisfy 0.5≦D1/D2≦0.69, and a distance H between the substrate-sideopening and the exit-side opening diameter D2 is set to satisfy0.3≦H/D2≦0.55. This configuration is preferable for clear and uniformirradiation by the lighting device.

According to a preferred embodiment of the present invention, themounting density of the plurality of LED chips with respect to thesubstrate-side opening area of the reflector is not less than 3.0/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED chips with respect to thesubstrate-side opening area of the reflector is not less than 25/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED chips with respect to thesubstrate-side opening area of the reflector is not less than 60/cm².

According to a preferred embodiment of the present invention, anoccupied area ratio of the plurality of LED chips to the substrate-sideopening area of the reflector is not less than 30%.

According to a preferred embodiment of the present invention, anoccupied area ratio of the plurality of LED modules to thesubstrate-side opening area of the reflector is not less than 70%.

This configuration is preferable for making the planar light sourceportion look like not a set of point light sources but a light-emittingsurface. The configuration in which the mounting density is not lessthan 60/cm² or the occupied area ratio is not less than 70% can berealized even when an interval of approximately 0.5 mm is securedbetween the LED modules, and has an advantage in which, as a so-calledmounter for mounting the LED modules on the substrate, a general one canbe used.

According to a preferred embodiment of the present invention, thelighting device further includes a housing made of metal which isdisposed on the side opposite to the reflector with respect to thesubstrate and includes a bottom portion with which the substrate is incontact, and a cylindrical portion connected integrally to the bottomportion. With this configuration, heat radiation from the LED module canbe promoted via the housing.

The surface of the reflector may be an uneven metal surface. Thisconfiguration is advantageous for uniformizing light from the lightingdevice.

A lighting device to be provided according to a second aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips, and a pair of mounting terminals spaced from eachother. The LED lamp has a shape and a size corresponding to a 40 Wstraight tube fluorescent lamp. The number of the plurality of LEDmodules is not less than 600.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.0 mm×0.6 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.6 mm×0.8 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a height not more than 0.2 mm.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 1000.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 4000.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 8000.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 12000.

A lighting device to be provided according to a third aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips and a pair of mounting terminals spaced from eachother. The LED lamp has a shape and a size corresponding to a 20 Wstraight tube fluorescent lamp. The number of the plurality of LEDmodules is not less than 290.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 480.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 1900.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 3900.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 5800.

A lighting device to be provided according to a fourth aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips and a pair of mounting terminals spaced from eachother. The LED lamp has a shape and a size corresponding to a 15 Wstraight tube fluorescent lamp. The number of the plurality of LEDmodules is not less than 200.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 330.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 1300.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 2700.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 4000.

A lighting device to be provided according to a fifth aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips and a pair of mounting terminals spaced from eachother. The LED lamp has a shape and a size corresponding to a 10 Wstraight tube fluorescent lamp. The number of the plurality of LEDmodules is not less than 150.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 250.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 1000.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 2000.

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules is not less than 3000.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.0 mm×0.6 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.6 mm×0.8 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a height not more than 0.2 mm.

An LED lamp to be provided according to a sixth aspect of the presentinvention has the form of an LED lamp including a band-shaped substrateand a plurality of LED chips arrayed on the substrate. This LED lampincludes a plurality of LED modules each including one or more of theLED chips and a pair of mounting terminals spaced from each other. Themounting density of the plurality of LED modules with respect to thearea of the substrate is not less than 3.0/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED modules with respect to thearea of the substrate is not less than 5.0/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED modules with respect to thearea of the substrate is not less than 20/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED modules with respect to thearea of the substrate is not less than 40/cm².

According to a preferred embodiment of the present invention, themounting density of the plurality of LED modules with respect to thearea of the substrate is not less than 60/cm².

According to a preferred embodiment of the present invention, the numberof the plurality of LED modules mounted in the width direction of thesubstrate is not less than 3.

According to a preferred embodiment of the present invention, themounting density of the plurality of LED modules in the longitudinaldirection of the substrate is larger than the mounting density of theplurality of LED modules in the width direction of the substrate.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.0 mm×0.6 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.6 mm×0.8 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a height not more than 0.2 mm.

A lighting device to be provided according to a seventh aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips and a pair of mounting terminals spaced from eachother. The occupied area ratio of the plurality of LED modules withrespect to the area of the substrate is not less than 20%, and each ofthe LED modules has a size not more than 4.0 mm×2.0 mm in a plan view.

A lighting device to be provided according to an eighth aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a plurality of LED chips arrayed on the substrate. ThisLED lamp includes a plurality of LED modules each including one or moreof the LED chips and a pair of mounting terminals spaced from eachother. The occupied area ratio of the plurality of LED modules withrespect to the area of the substrate is not less than 30%.

According to a preferred embodiment of the present invention, theoccupied area ratio of the plurality of LED modules to the area of thesubstrate is not less than 35%.

According to a preferred embodiment of the present invention, theoccupied area ratio of the plurality of LED modules to the area of thesubstrate is not less than 45%.

According to a preferred embodiment of the present invention, theoccupied area ratio of the plurality of LED modules to the area of thesubstrate is not less than 70%.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.0 mm×0.6 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a size not more than 1.6 mm×0.8 mm in a plan view.

According to a preferred embodiment of the present invention, each ofthe LED modules has a height not more than 0.2 mm.

According to a preferred embodiment of the present invention, theoccupation ratio of the plurality of LED modules in the longitudinaldirection of the substrate is larger than the occupation ratio of theplurality of LED modules in the width direction of the substrate.

According to a preferred embodiment of the present invention, theplurality of LED modules include LED modules which emit light differentin wavelength from each other.

According to a preferred embodiment of the present invention, theplurality of LED modules include a plurality of LED modules which emitwhite light and a plurality of LED modules which are arrayed discretelyand emit red light, and whose proportion to the total is smaller thanthat of the plurality of LED modules that emit white light.

According to a preferred embodiment of the present invention, a currentflowing in each of the LED chips is not more than 20% of a rated currentof the LED chip.

A lighting device to be provided according to a ninth aspect of thepresent invention has the form of an LED lamp including a band-shapedsubstrate and a planar light source portion including a plurality of LEDchips arrayed on the substrate.

According to a preferred embodiment of the present invention, thelighting device further includes a case having a circular tubularsectional shape for housing the substrate.

According to a preferred embodiment of the present invention, theplurality of LED chips belong to a plurality of groups connected inseries to each other, and the plurality of LED chips belonging to eachgroup are connected in parallel to each other.

According to a preferred embodiment of the present invention, thelighting device includes a plurality of LED modules each including oneor more of the LED chips and a pair of mounting terminals spaced fromeach other. Each of the plurality of LED modules is disposed in aposture in which the pair of mounting terminals are spaced from eachother in the width direction of the substrate, and the plurality of LEDmodules are arrayed so as to form a plurality of rows disposed parallelto each other along the longitudinal direction of the substrate.

According to a preferred embodiment of the present invention, theplurality of LED modules are arrayed zigzag.

According to a preferred embodiment of the present invention, thesubstrate is a flexible wiring substrate having flexibility andincluding a laminated resin layer and a metal wiring layer, and has acircular or arc sectional shape.

According to a preferred embodiment of the present invention, the casehas a straight tube shape, a pair of projecting pieces projecting inwardwithin a plane parallel to a central axis of the case are formedintegrally with the case, and the substrate is restricted from movingradially with respect to the case by the projecting pieces.

With this configuration, light emitted from the plurality of LED chips(or the plurality of LED modules) looks like not light from point lightsources but planar light to the naked eye. Therefore, to this planarlight, it is not necessary to apply, for example, diffusion to an extentso as to make light from a plurality of point light sources look likelight from a planar light source. Therefore, improper attenuation oflight from the LED lamp can be avoided, and the luminous efficiency ofthe LED lamp can be increased. As the mounted number of the plurality ofLED chips is increased, the current value to be supplied to each LEDchip can be relatively reduced. This is advantageous for reducing theratio of energy to be consumed for heat generation to the energysupplied to the LED chips, and suitable for increasing the luminousefficiency of the LED lamp.

Other features and advantages of the present invention will be clarifiedfrom the detailed description given below with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a lighting device based on a firstpreferred embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG. 1.

FIG. 3 is a plan view showing a substrate and a wiring pattern of thelighting device shown in FIG. 1.

FIG. 4 is an enlarged plan view showing a portion S1 of FIG. 3.

FIG. 5 is an enlarged plan view showing a portion S2 of FIG. 3.

FIG. 6 is a plan view showing an LED module to be used in the lightingdevice shown in FIG. 1.

FIG. 7 is a sectional view taken along line VII-VII of FIG. 6.

FIG. 8 is a bottom view showing an LED module to be used in the lightingdevice shown in FIG. 1.

FIG. 9 is a circuit diagram showing the lighting device shown in FIG. 1.

FIG. 10 is a circuit diagram for describing a configuration of a powersupply unit.

FIG. 11 is a graph showing relationships between a current and luminousefficiencies of the LED modules to be used in the lighting device shownin FIG. 1.

FIG. 12 is a diagram showing a relationship between the number of LEDmodules and illuminance.

FIG. 13 is a view for describing an illuminance unevenness calculationmethod.

FIG. 14 is a diagram showing a relationship between the number of LEDmodules and illuminance.

FIG. 15 is a diagram showing a relationship among a current per one LEDmodule, illuminance, and illuminance unevenness.

FIG. 16A is a graph showing changes in distribution of relativeilluminance B according to the distance H.

FIG. 16B is a graph showing changes in distribution of relativeilluminance B according to the diameter D2 and distance H.

FIG. 17 is a diagram showing changes in efficiency according to thedistance H.

FIG. 18A is a diagram showing relative illuminance distributions whenusing reflectors of various sizes.

FIG. 18B is a diagram showing relative illuminance distributions whenusing reflectors of various sizes.

FIG. 18C is a diagram showing relative illuminance distributions whenusing reflectors of various sizes.

FIG. 18D is a diagram showing relative illuminance distributions whenusing reflectors of various sizes.

FIG. 19 is a plan view showing another example of a substrate and awiring pattern to be used in the lighting device shown in FIG. 1.

FIG. 20 is a plan view showing another example of an LED module to beused in the lighting device shown in FIG. 1.

FIG. 21 is a sectional view taken along line XXI-XXI of FIG. 20.

FIG. 22 is a bottom view showing another example of an LED module to beused in the lighting device shown in FIG. 1.

FIG. 23 is a plan view showing another example of a substrate and awiring pattern to be used in the lighting device shown in FIG. 1.

FIG. 24 is a major portion sectional view taken along line XXIV-XXIV ofFIG. 23.

FIG. 25 is a plan view showing still another example of a substrate anda wiring pattern to be used in the lighting device shown in FIG. 1.

FIG. 26 is a sectional view showing a lighting device according to asecond preferred embodiment of the present invention.

FIG. 27 is a sectional view showing a lighting device according to athird preferred embodiment of the present invention.

FIG. 28 is a perspective view showing an example of an LED lampaccording to a fourth preferred embodiment of the present invention.

FIG. 29 is a major portion sectional view taken along line XXIX-XXIX ofFIG. 28.

FIG. 30 is a sectional view taken along line XXX-XXX of FIG. 29.

FIG. 31 is a major portion enlarged plan view showing a substrate andLED modules of the LED lamp shown in FIG. 28.

FIG. 32 is a plan view showing an example of an LED module of the LEDlamp shown in FIG. 28.

FIG. 33 is a sectional view taken along line XXXIII-XXXIII of FIG. 32.

FIG. 34 is a bottom view showing the LED module shown in FIG. 32.

FIG. 35 is a circuit diagram showing the LED lamp shown in FIG. 28.

FIG. 36 is a major portion enlarged plan view showing an exemplaryvariation of a substrate and LED modules of the LED lamp shown in FIG.28.

FIG. 37 is a plan view showing an exemplary variation of an LED moduleof the LED lamp shown in FIG. 28.

FIG. 38 is a sectional view taken along line XXXVIII-XXXVIII of FIG. 37.

FIG. 39 is a bottom view showing the LED module shown in FIG. 37.

FIG. 40 is a plan view showing another exemplary variation of an LEDmodule of the LED lamp shown in FIG. 28.

FIG. 41 is a sectional view taken along line XXXXI-XXXXI of FIG. 40.

FIG. 42 is a bottom view showing the LED module shown in FIG. 40.

FIG. 43 is a major portion perspective view showing an example of an LEDlamp according to a fifth preferred embodiment of the present invention.

FIG. 44 is a sectional view taken along line XXXXIV-XXXXIV of FIG. 43.

FIG. 45 is a major portion perspective view showing an example of an LEDlamp based on a sixth preferred embodiment of the present invention.

FIG. 46 is a major portion sectional view taken along line XXXXVI-XXXXVIof FIG. 45.

FIG. 47 is a sectional view taken along line XXXXVII-XXXXVII of FIG. 46.

FIG. 48 is a sectional view showing an example of a conventional LEDlamp.

MODES FOR CARRYING OUT THE INVENTION

FIG. 1 and FIG. 2 show a lighting device according to a first preferredembodiment of the present invention. The lighting device A1 of thepresent preferred embodiment includes a substrate 1, a plurality of LEDmodules 3, a reflector 4, a housing 5, a connector 6, and a holder 7.The lighting device A1 may be used as a so-called downlight by beinginstalled in an opening space provided on a ceiling with an upside downposition in the z direction of FIG. 2.

The substrate 1 is, for example, an aluminum plate the surface of whichis insulated, and is for mounting a plurality of LED modules 3. In thepresent preferred embodiment, the substrate 1 is circular, and has adiameter of approximately 66 mm. The region in which the plurality ofLED modules 3 are mounted is a circular region with a diameter ofapproximately 50 to 60 mm.

As shown in FIG. 3, on the substrate 1, a wiring pattern 2 is formed.The wiring pattern 2 is made of a metal film of, for example, copper,and is for mounting a plurality of LED modules 3 and supplying electricpower thereto. The wiring pattern 2 includes an anode electrode 21A, acathode electrode 21B, a plurality of pad portions 22, a plurality ofanode folding portions 24A, a plurality of cathode folding portions 24B,a plurality of oblique joint portions 25, a straight joint portion 26,an anode connecting portion 27A, and a cathode connecting portion 27B.In the wiring pattern 2, portions other than the portions for mountingthe LED modules 3 are covered by an insulating layer (not shown) withhigh reflectance, for example, white resist.

The anode electrode 21A and the cathode electrode 21B are for connectingan electric wire (not shown) extending from a connector 6, and aredisposed close to one side in the x direction of the substrate 1.

The plurality of pad portions 22 are portions on which the plurality ofLED modules 3 are mounted. The pad portions 22 include an anode linearportion 23A (black in the drawing) and a cathode linear portion 23B(gray in the drawing). The anode linear portion 23A and the cathodelinear portion 23B extend in the x direction, and are disposed parallelto each other at intervals in the y direction which is orthogonal to thex direction. Accordingly, all of the plurality of pad portions 22 extendalong the x direction. Most of the plurality of pad portions 22 aredisposed parallel to each other at intervals in the y direction.Further, some pad portions 22 are disposed in series at intervals in thex direction.

FIG. 4 is a detailed view of the portion S1 of FIG. 3. On each padportion 22, a plurality of LED modules 3 are mounted. The LED module 3includes an LED chip 31, a resin package 32, a substrate 33, and a pairof mounting terminals 34 as shown in FIG. 6 to FIG. 8. The LED module 3has approximately a width of 0.8 mm, a length of 1.6 mm, and a thicknessof 0.5 mm, and is configured as a small-sized and very-thin LED module.

The substrate 33 is an insulating substrate which has a substantiallyrectangular shape in a plan view, and is made of, for example, glassepoxy resin. On the surface of the substrate 33, an LED chip 31 ismounted. On the back surface of the substrate 33, a pair of mountingterminals 34 are formed. The thickness of the substrate 33 is set toapproximately 0.08 mm to 0.1 mm. The LED chip 31 is a light source ofthe LED module 3, and capable of emitting, for example, visible light.The resin package 32 is for protecting the LED chip 31. The resinpackage 32 is molded by using, for example, an epoxy resin havingtranslucency for light generated by the LED chip 31 or a translucentresin containing a fluorescent material which is excited by the lightfrom the LED chip 31 to emit light with a different wavelength. Forexample, by mixing blue light from the LED chip 31 and yellow light fromthe fluorescent material contained in the resin package 32, the LEDmodule 3 can irradiate white light. Instead of the fluorescent materialthat emits yellow light, a fluorescent material that emits red light anda fluorescent material that emits green light may be mixed and used.

The LED module 3 is mounted on the pad portion 22 by, for example,soldering one of the pair of mounting terminals 34 to the anode linearportion 23A and the other mounting terminal to the cathode linearportion 23B. Accordingly, the plurality of LED modules 3 mounted on onepad portions 22 are connected in parallel to each other.

In the portion S1 shown in FIG. 4, two groups consisting of a pluralityof LED modules 3 connected in parallel are disposed across the obliquejoint portion 25. Two pad portions 22 disposed on both sides of theoblique joint portion 25 have the same disposition of the anode linearportion 23A and the cathode linear portion 23B in the y direction. Theoblique joint portion 25 joins the anode linear portion 23A of one ofthe pad portions 22 and the cathode linear portion 23B of the other padportion 22. Accordingly, the plurality of LED modules 3 belonging tothese two groups are connected in series to each other.

In the portion S2 shown in FIG. 5, two groups consisting of a pluralityof LED modules 3 connected in parallel to each other are disposed acrossa straight joint portion 26. The two pad portions 22 disposed on bothsides of the straight joint portion 26 have dispositions of the anodelinear portions 23A and cathode linear portions 23B inverse to eachother in the y direction. The straight joint portion 26 joins the anodelinear portion 23A of one of the pad portions 22 and the cathode linearportion 23B of the other pad portion 22. Accordingly, the plurality ofLED modules 3 belonging to these two groups are connected in series toeach other.

As shown in FIG. 3, pad portions 22 adjacent to each other in the ydirection of the plurality of pad portions 22 are connected by the anodefolding portion 24A and the cathode folding portion 24B. Morespecifically, the anode folding portion 24A joins anode linear portions23B adjacent to each other in the y direction. The cathode foldingportion 24B joins cathode linear portions 23 adjacent to each other inthey direction.

In the path from the anode electrode 21A to the cathode electrode 21B, aplurality of pad portions 22 and, in order from the anode electrode 21Aside, one straight joint portion 26 and seven oblique joint portions 25are disposed. Accordingly, the plurality of LED modules 3, that is, theplurality of LED chips 31 are connected as shown in FIG. 9. In thepresent preferred embodiment, 603 LED modules 3 (LED chips 31) are used.These LED modules 3 are divided into nine groups 31A. The group 31Aincludes 67 LED modules 3 connected in parallel to each other. Thesenine groups 31A are connected in series to each other by one straightjoint portion 26 and seven oblique joint portions 25.

In the present preferred embodiment, 603 LED modules 3 are arrayedzigzag on the substrate 1. As power supply specifications for making theplurality of LED modules 3 emit light, the voltage between the anodeelectrode 21A and the cathode electrode 21B is approximately 27V, thevoltage Vf of each LED module 3 is approximately 3.0V, and the currentIf is approximately 4.0 mA. When the plurality of LED modules 3 mountedat a high density emit light, the light looks like not a set of aplurality of point light sources but surface luminescence to the nakedeye. Specifically, the region in which the plurality of LED modules 3are mounted forms a planar light source portion 3A.

As shown in FIG. 3, in the region of approximately ⅔ from the lower endof the substrate 1, a plurality of anode folding portions 24A arepositioned on the left side, and a plurality of cathode folding portions24B are positioned on the right side. From the portion where thestraight joint portion 26 is provided, in the region of approximately ⅓from the upper end of the substrate 1, a plurality of anode foldingportions 24A are positioned on the right side, and a plurality ofcathode folding portions 24B are positioned on the left side. The anodeconnecting portion 27A connects the anode electrode 21A and the anodefolding portion 24A on the upper right portion of the substrate 1. Thecathode connecting portion 27B connects the cathode electrode 21B andthe cathode folding portion 24B on the lower right portion of thesubstrate 1.

As shown in FIG. 1 and FIG. 2, the reflector 4 has a cone shape whichhas openings 41 and 42 and a sectional size that becomes larger withincreasing distance from the substrate 1, and is made of, for example,aluminum. The reflector 4 surrounds a plurality of LED modules 4, andreflects light emitted from the LED modules toward the z direction. Inthe present preferred embodiment, the diameter D1 of the opening 41 is60 mm, the diameter D2 of the opening 42 is 100 mm, and the distance His 50 mm. In addition, even with a configuration in which the diameterD1 is 52 mm to 62 mm, the diameter D2 is 90 mm, and the distance H isapproximately 40 mm, preferable irradiation is also realized. The innersurface of the reflector 4 is, for example, an uneven Al-plated surface.

The planar light source portion 3A faces a space to be illuminated(illumination space) through the opening 41. In the present preferredembodiment, the mounting density of the plurality of LED modules 3 perunit area of the opening 41 is set to 31/cm². This mounting density isapproximately 39% in terms of a ratio of the occupied area of theplurality of LED modules 3 to the area of the opening 41.

The housing 5 is made of, for example, aluminum, and supports thesubstrate 1 and the reflector 4. When the LED modules 3 emit light, heatfrom the LED modules 3 is transmitted to the reflector 4 and the housing5 via the substrate 1. Accordingly, heat radiation of the LED modules 3is enhanced. The connector 6 is connected to a connector (not shown) ofa building side when the lighting device A1 is mounted on a ceiling. Aholder 7 is formed by bending, for example, a stainless-steel (SUS301)plate. The holder 7 engages with a part of the ceiling to hold thelighting device A1 when the lighting device A1 is attached to theceiling.

Inside the housing 5, a power supply substrate 60A forming a powersupply unit is housed. The power supply substrate 60A is supported at adistance from a support substrate 8 by columnar supports 9 and 9 made ofa resin erected inside the housing 5 from the support substrate 8. Thesupport substrate 8 is fixed to the housing 5 on the side opposite tothe substrate 1. The connector 6 is attached to the support substrate 1outside the housing 5 on the same side as the housing 5.

FIG. 10 is an electric circuit diagram for describing an electricalconfiguration of the lighting device A1. A series circuit of theplurality of LED groups 31A is connected to the power supply unit 60serving as a constant current power supply. The power supply unit 60includes a surge protection circuit 61, a filter circuit 62, arectifying circuit 63, a control circuit 64, and a reverse voltageprotection circuit 65.

The surge protection circuit 61 includes a fuse 69 interposed in one ofa pair of power feeders 67 and 68 to be connected to a commercial ACpower supply 66, and a varistor 70 connected between the power feeders67 and 68. With this configuration, the power supply unit 60 isprotected from a lightning surge, etc.

The filter circuit 62 includes an inductor 71 interposed between thepower feeders 67 and 68 and capacitors 72 and 73 connected between thepower feeders 67 and 68 on both sides of the inductor 71. With thisconfiguration, filtering for removing noise transmitted from the ACpower supply is performed.

The rectifying circuit 63 is configured by bridge-connecting four diodes74. With this configuration, the rectifying circuit 63 performsfull-wave rectification of an alternating current from the power feeders67 and 68.

The control circuit 64 includes a constant current driver 75 consistingof an integrated circuit (IC), smoothing capacitors 76 to 78, and acurrent setting resistor element 79. To power supply terminals 75 a and75 b of the constant current driver 75, electric power is supplied fromthe rectifying circuit 63 via DC power feeders 80 and 81. Between theseDC power feeders 80 and 81, the smoothing capacitor 76 is connected.This smoothing capacitor 76 smoothes an input voltage to be input intothe constant current driver 75. Between one of the DC power feeders 82and the control terminal 75 c of the constant current driver 75, thesmoothing capacitor 77 is connected. This smoothing capacitor 77 has afunction to smooth the voltage inside the constant current driver 75. Onthe other hand, between output terminals 75 d and 75 e of the constantcurrent driver 75 and a pair of output terminals 82 and 83 of thecontrol circuit 64, a pair of output lines 84 and 85 are connected,respectively. Between these output lines 84 and 85, the smoothingcapacitor 78 is connected. This smoothing capacitor 78 smoothes theoutput voltage of the constant current driver 75. Between the outputterminal 75 e (output line 85) on the negative terminal side and thecontrol terminal 75 c, the current setting resistor element 79 isconnected. The constant current driver 75 operates so that a constantcurrent corresponding to a resistance value of the current settingresistor element 79 flows between the output terminals 75 d and 75 e.Therefore, a resistor element with a proper resistance value is selectedaccording to a necessary current value and connected as the currentsetting resistor element 79.

The reverse voltage protection circuit 65 includes a pair of zenerdiodes 86 and 87 connected in series between the output lines 84 and 85.When a reverse voltage is applied between the output lines 84 and 85,the reverse voltage protection circuit 65 prevents the reverse voltagefrom being applied to the LED modules 3, and accordingly protects theLED modules 3 from breakage.

Between the output terminals 82 and 83, a series circuit of theplurality of LED groups 31A is connected via lead wires 88 and 89. Theplurality of LED modules 3 constituting each LED group 31A are connectedin parallel to the power supply unit 60. Therefore, a current controlledto a constant current which is supplied from the power supply unit 60 isdistributed to the plurality of LED modules 3 constituting each group31A. Accordingly, a current (drive current) flowing in each LED module 3is determined according to a current value supplied by the power supplyunit 60 and the number of LED modules 3 (connected in parallel) in eachgroup 31A. Therefore, the resistance value of the current settingresistor element 79 and the number of LED modules 3 (connected inparallel) constituting each group 31A are designed so that the drivecurrent of each LED module 3 has a desired value (for example, 4 mA).

Next, operations of the lighting device A1 will be described.

According to the present preferred embodiment, light is emitted from theplanar light source portion 3A constituted by the plurality of LEDmodules 3. Light emitted from the planar light source portion 3Aadvances mainly in the normal direction of the surface of the substrate1, and does not advance in various directions. Therefore, as comparedwith a downlight including a point light source typified by, forexample, a halogen lamp, the reflector 4 for directing light toward apredetermined range can be made smaller. Therefore, the lighting deviceA1 can be downsized, and the mounting space on the ceiling to which thelighting device A1 is attached can be saved. Zigzag array of the LEDmodules 3 is suitable for obtaining uniform surface luminescence.

The current If flowing in each LED module 3 (LED chip 31) is acomparatively low current of approximately 4.0 mA. When driving the LEDmodule 3 with such a low current If, the luminous efficiency thereofreaches a little less than 70 Lm/W. As a result, when electric power of7.0 W is supplied, even if inevitable absorption and light leakage ofthe lighting device A1 causes loss, the lighting device A1 realizesbrightness of 413 Lm. The luminous efficiency in this case is 59 Lm/W,and is much higher than that of a light source using a filament such asa halogen lamp, so that dramatic power-savings are realized.

FIG. 11 shows a relationship between a current If flowing in one LEDmodule 3 and luminous efficiency Ef. The LED module 3 of the presentpreferred embodiment is equivalent to Type A of this drawing. Therelationship shown in FIG. 11 indicates that excellent luminousefficiency Ef is obtained in the range of 2 mA to 8 mA (more preferably,2 mA to 4 mA) of the current If flowing in the LED module 3.Particularly, when the current If is 4 mA, the LED module 3 can be madeto emit light with the highest luminous efficiency. The rated current ofthe LED module 3 is approximately 20 mA, so that in order to realizehigh-efficiency luminescence, the current If is set to 10% to 40% of therated current (If=2 mA to 8 mA). Further, by setting the current If to20%±3% (If=4 mA), the efficiency of a single LED module 3 becomesmaximum.

On the other hand, results of investigation on the luminous efficiency,etc., as a whole of the lighting device A1 are shown in the followingTable 1.

TABLE 1 Trial Number Power product of Current consumption IlluminanceIlluminance example LEDs mA W at 1 m Lx/W unevenness A 603 4.0 7.9 412.152.2  2% B 302 8.0 7.9 410.6 52.0  5% C 153 16.0 7.9 379.5 48.0 12% D117 20.8 7.9 361.9 45.8 21%

The trial product example A has the above-described configuration inwhich 603 LED modules 3 are mounted on the substrate 1. The trialproduct example B is configured such that 302 LED modules 3 are mountedon the substrate 1 by omitting every other LED modules 3 from the trialproduct example A. In this case, the number of LED modules 3 (connectedin parallel) constituting each LED group 31A is reduced to approximatelyhalf, and accordingly, the drive current in each LED module 3 becomestwice (8 mA) the drive current of 4 mA of the trial product example A.In detail, by connecting a total of 9 groups including five groups 31Aeach consisting of 34 LED modules 3 and four groups each consisting of33 LED modules 3 in series, a total of 302 LED modules 3 are used. Ofcourse, other omitting methods can also be used, and it is also possiblethat, for example, a total of 306 LED modules 3 may be used byconnecting nine groups each consisting of 34 LED modules 3 in series.

The trial product example C has a configuration in which 153 LED modules3 are mounted on the substrate 1 by further omitting every other LEDmodules 3 from the trial product example B. In this case, the number ofLED modules 3 (connected in parallel) constituting each LED group 31A isreduced to approximately ¼ of that in the case of the trial productexample A, and accordingly, the drive current in each LED module 3 is 16mA that is four times the drive current in the case of the trial productexample A. The trial product example D is configured such that thenumber of LED modules 3 is reduced to ⅕ by uniformly omitting LEDmodules 3 from the trial product example A. In this case, the number ofLED modules 3 constituting each LED group 31A is reduced toapproximately ⅕ of that in the case of the trial product example A, andaccordingly, the drive current in each LED module 3 is 20.8 mA that isapproximately five times the drive current in the case of the trialproduct example A.

“Power consumption” is power consumption of all LED modules 3.“Illuminance at 1 m” is an illuminance (Lx) measured at a distance of 1m from the exit-side opening 42 of the reflector 4 in the normaldirection of the substrate 1. “Lx/W” is a value obtained by dividing theilluminance at 1 m by the power consumption, and corresponds to luminousefficiency of the entire lighting device. “Illuminance unevenness” meansthe degree of illuminance distribution unevenness.

The relationship between the number of LED modules 3 and the illuminanceis shown in FIG. 12. This drawing and Table 1 shown above indicates thatthere is no substantial difference in illuminance between the trialproduct examples A and B. Further, in Table 1, no significant differencein luminous efficiency is found between the trial product examples A andB. Therefore, the trial product example A is more advantageous in theluminous efficiency of each LED module 3; however, there are nodifferences in the illuminance and the luminous efficiency of theentirety, so that the trial product example B including the smallernumber of LED modules 3 is more advantageous because its cost and numberof manufacturing processes are smaller.

FIG. 13 is a view for describing a method for obtaining the illuminanceunevenness, and shows an illuminance histogram. Steps for obtaining theilluminance unevenness are as follows. First, the illuminance ismeasured at a plurality of different positions on a 3 m-square lightreceiving surface (surface perpendicular to the normal direction of thesubstrate 1) centered at a position at a distance of 1 m from theexit-side opening 42 of the reflector 4 in the normal direction of thesubstrate 1. Next, a frequency distribution of the illuminance values isobtained, and the histogram as shown in FIG. 13 is prepared. Then, astraight line L1 connecting the lowest frequency position a and thesecond lowest frequency position b is obtained. There is a large amountof noise around the illuminance upper limit and the illuminance lowerlimit, so that straight lines L2 and L3 for excluding the range lowerthan a predetermined lower limit threshold c and a range higher than anupper limit threshold d are obtained. Further, in the illuminancesection between the straight lines L2 and L3, a straight line L4circumscribed about a frequency distribution curve L5 is obtained.Accordingly, a quadrilateral surrounded by the straight lines L1 to L4is obtained. An area (reference area) Sref of this quadrilateral isobtained. Next, an area (illuminance unevenness area) Su between thestraight line L4 and the frequency distribution curve L5 is obtained. Aratio of the illuminance unevenness area Su to the reference area Srefis expressed as illuminance unevenness (%) by percentage(=(Su/Sref)×100).

The relationship between the number of LED modules 3 and the illuminanceunevenness is shown in FIG. 14. In the trial product example A and thetrial product example B, the illuminance unevenness is not more than 5%;however, in the trial product examples C and D, the illuminanceunevenness is over 10%. In the case where the illuminance unevenness isgreat, when an object is near the lighting device A1, a shading patternsuch as stripes is observed on the object surface. In detail, when adownlight is mounted on the ceiling near a wall surface, a shadingpattern caused by illuminance unevenness may be formed on the wallsurface. Therefore, it is preferable that the illuminance unevenness isreduced to the level of the trial product examples A and B.

FIG. 15 is a graph showing the relationship among a drive current ofeach LED module 3, an illuminance at 1 m, and illuminance unevennessbased on Table 1 shown above. FIG. 15 indicates that a necessaryilluminance can be secured and the illuminance unevenness can be reducedto an acceptable range by setting a drive current per one LED module 3,that is, per one LED chip 31 to not more than 8 mA.

On the other hand, in the trial product example A, the mounting densityof the LED modules 3 is approximately 31/cm², or the occupied area ratiois approximately 39%. In the trial product example B, the mountingdensity of the LED modules 3 is approximately 15/cm², or the occupiedarea ratio is approximately 20%. Further, in the trial product exampleC, the mounting density of the LED modules 3 is approximately 8/cm², orthe occupied area ratio is approximately 10%. In the trial productexample D, the mounting density of the LED modules 3 is approximately6/cm², or the occupied area ratio is approximately 8%. Although themounting density and the occupied area ratio within the ranges of thetrial product examples A and B are preferable, even in the case of thetrial product examples C and D, the planar light source portion 3A canlook like a light emitting surface which emits uniform light. Forobtaining such uniform surface luminescence, it is preferable that themounting density is set to not less than 5/cm² (preferably not less than12/cm², more preferably not less than 25/cm²) or the occupied area ratiois set to not less than 6% (preferably not less than 15%, morepreferably not less than 30%).

The mounting density in the trial product example A is obtained based onthe calculation formula “603/(2.5 cm×2.5 cm×3.14).” The occupied arearatio in the trial product example A is obtained based on thecalculation formula “(603×1.6 mm×0.8 mm)/(2.5 cm×2.5 cm×3.14).” In othertrial product examples, the above-described values are also obtainedbased on corresponding calculation formulas.

In the lighting device A1, by providing the oblique joint portions 25,the plurality of LED modules 3 arrayed systematically in the x directioncan be connected so as to belong to a plurality of groups connected inseries to each other. The systematic array of the plurality of LEDmodules 3 is important for obtaining uniform surface luminescence.Connection of the plurality of LED modules 3 so as to belong to theplurality of groups connected in series to each other is advantageousfor setting the current If to be supplied to each LED module 3 to a lowcurrent suitable for high-efficiency luminescence and setting thevoltage between the anode electrode 21A and the cathode electrode 21B toapproximately 27V that realizes comparatively easy constant currentcontrol.

As shown in FIG. 3, the straight joint portion 26 is a boundary wherethe disposition in the x direction of the plurality of anode foldingportions 24A and the plurality of cathode folding portions 24B isreversed. Accordingly, on the side on which the anode electrode 21A andthe cathode electrode 21B are disposed, the anode folding portions 24Aand the cathode folding portions 24B are disposed so as to face theanode electrode 21A and the cathode electrode 21B. Therefore, the anodeconnecting portion 27A and the cathode connecting portion 27B extendingfrom the anode electrode 21A and the cathode electrode 21B can beshortened.

By setting the diameters D1 and D2 and the distance H to the dimensionsdescribed above, the illuminance in the irradiation range of thelighting device A1 can be distributed suitably as a downlight. FIG. 16Ashows illuminance distributions when the distance H is changed in thecase where the diameter D1=60 mm and the diameter D2=100 mm. In detail,illuminance distributions when H=55 mm, 50 mm, 45 mm, 40 mm, 35 mm, 30mm, 25 mm, 20 mm, 15 mm, 10 mm, and 0 mm are shown by curves,respectively. The horizontal axis indicates a radius R centered at thefront face of the lighting device A1 on an irradiation surface at adistance of 1 m from the lighting device A1, and the vertical axisindicates a relative illuminance B on the irradiation surface. Therelative illuminance B indicates a relative illuminance when theilluminance in the case of H=55 mm and R=0 mm is defined as 1.

As is understood from this drawing, when H=55 mm (H/D2=0.55) to 30 mm(H/D2=0.3), the relative illuminance B at R=0 mm is almost 1.0, and as Rincreases, the relative illuminance B gently decreases. On the otherhand, when H=25 mm to 0 mm, the relative illuminance B at R=0 mmdecreases significantly. This means that, if H is not more than 25 mm,light leaks to an improperly wide range. Therefore, H≧30 mm ispreferable for clearly irradiating the irradiation range. In order toobtain such clear irradiation, the reflector 4 is preferably configuredso as to satisfy 0.5≦D1/D2≦0.69 and 0.3≦H/D2≦0.55.

FIG. 16B shows illuminance distributions when the diameter D1=62 mm andthe diameter D2 and distance H are changed to various values. Thehorizontal axis indicates the radius R centered at the front face of thelighting device A1 on an illumination surface at a distance of 1 m fromthe lighting device A1, and the vertical axis indicates the relativeilluminance B on the illumination surface. The relative illuminance B isa relative illuminance when the illuminance under conditions of H=45 mm,D2=100, and R=0 mm is defined as 1. FIG. 16B shows the relativeilluminances B when the distance H and the diameter D2 are set to thefollowing combinations.

H=55 mm, D2=100 mm

H=50 mm, D2=100 mm

H=45 mm, D2=100 mm

H=40 mm, D2=100 mm

H=55 mm, D2=97 mm

H=50 mm, D2=97 mm

H=45 mm, D2=97 mm

H=40 mm, D2=97 mm

H=55 mm, D2=95 mm

H=50 mm, D2=95 mm

H=45 mm, D2=95 mm

H=40 mm, D2=95 mm

H=55 mm, D2=90 mm

H=50 mm, D2=90 mm

H=45 mm, D2=90 mm

H=40 mm, D2=90 mm

H=0 mm, D2=0 mm

FIG. 17 shows results of investigation on the efficiency when thedistance H was set to various values in the case where D1=60 mm andD2=100 mm (D1/D2=0.6). Here, “efficiency” means a ratio of light amountthat enters a 3 m-square light receiving surface centered at a positionat a distance of 1 m from the exit-side opening 42 of the reflector 4 inthe normal direction of the substrate 1 to the total outgoing lightamount. High efficiency is realized in the range of H≧30 mm, and theefficiency does not greatly change in the range of H≧40 even if thedistance H is increased. Therefore, from the point of view of heightreduction, H=30 mm to 40 mm is preferable.

FIG. 18A to FIG. 18D are graphs showing results of measurement of theemission illuminance in the reflector 4 the dimensions of which aredetermined as shown in the following No. 1 to No. 9. No. 10 is arelative illuminance when no reflector is provided. “Emissionilluminance” is a value on a 3 m-square light receiving surface centeredat a position at a distance of 1 m from the exit-side opening 42 of thereflector 4 in the normal direction of the substrate 1. “Position” onthe horizontal axes of the graphs indicates a distance from the centerposition of the square light receiving surface as described above.

No. 1 D1=52 mm D2=90 mm H=35 mm

(D1/D2=0.58, H/D2=0.39)

No. 2 D1=52 mm D2=90 mm H=40 mm

(D1/D2=0.58, H/D2=0.44)

No. 3 D1=52 mm D2=90 mm H=45 mm

(D1/D2=0.58, H/D2=0.50)

No. 4 D1=47 mm D2=90 mm H=35 mm

(D1/D2=0.52, H/D2=0.39)

No. 5 D1=47 mm D2=90 mm H=40 mm

(D1/D2=0.52, H/D2=0.44)

No. 6 D1=47 mm D2=90 mm H=45 mm

(D1/D2=0.52, H/D2=0.50)

No. 7 D1=42 mm D2=90 mm H=35 mm

(D1/D2=0.47, H/D2=0.39)

No. 8 D1=42 mm D2=90 mm H=40 mm

(D1/D2=0.47, H/D2=0.44)

No. 9 D1=42 mm D2=90 mm H=45 mm

(D1/D2=0.47, H/D2=0.50)

No. 11 D1=62 mm D2=100 mm H=55 mm

(D1/D2=0.62, H/D2=0.55)

No. 12 D1=62 m D2=100 mm H=40 mm

(D1/D2=0.62, H/D2=0.40)

No. 13 D1=62 mm D2=90 mm H=40 mm

(D1/D2=0.69, H/D2=0.44)

No. 14 D1=52 mm D2=90 mm H=40 mm

(D1/D2=0.58, H/D2=0.44)

When the diameter of the ceiling hole is set to 100 mm, the diameter D2of the exit-side opening 42 can be set to approximately 90 mm. In thiscase, when D1=52 mm is set, as shown in FIG. 18A, in the case where thedistance H from the exit-side opening surface to the substrate 1 ischanged to H=35 mm, H=40 mm, and H=45 mm, the emission illuminancebecomes values with waveforms shown in No. 1, No. 2, and No. 3 in thesecases, and these are substantially equal to each other.

On the other hand, when D2=90 mm and D1=47 mm, as shown in FIG. 18B, inthe case where the distance H is changed to H=35 mm, H=40 mm, and H=45mm, the emission illuminance becomes values with waveforms shown in No.4, No. 5, and No. 6 in these cases, and variation occurs in emissionilluminance.

Further, as shown in FIG. 18C, when D1=42 mm, in the case where thedistance H is changed to H=35 mm, H=40 mm, and H=45 mm, greatervariation occurs in emission illuminance as composed to the case ofD1=47 mm.

Based on the above-described measurement results, when the reflector 4with a large D2=90 mm and D1=not more than 45 mm is used, emissionilluminance due to the height greatly varies when the height H ischanged according to design changes. Therefore, when setting D2=90 mm,in order to prevent the emission illuminance from being varied by designchanges, D1 is preferably not less than 45 mm. Also, in the light of themounting density of the LED modules, D1 is preferably not less than 45mm. According to this, the range of D1/D2=not less than 0.5 ispreferable.

As shown in FIG. 18D, when the reflector 4 with D2=90 mm and H=40 mm isused, in the case where D1=52 mm, emission illuminance with the waveformshown in No. 14 can be obtained.

On the other hand, when D1=62 mm is set while D2=90 mm and H=40 mm, likethe emission illuminance with the waveform shown in No. 13, thecondensation effect becomes smaller and the emission illuminanceimmediately under the equipment becomes smaller as compared with theemission illuminance shown by the waveform of No. 14.

For the above-described reasons, when H=40 mm and the diameter D2 of theexit-side opening is increased to D2=90 mm, it is preferable that D1=notmore than 62 mm, that is, D1/D2=not more than 0.69 (more preferably, notmore than 0.67).

It was found by the inventors' research that the reduction in thecurrent If to be supplied to each LED module 3 is advantageous forreducing variation in the voltage Vf for setting the current If to adesired value. The inventors measured the voltage Vf when the current Iffor the plurality of LED modules 3 was regulated to 10, 100, 200, and300 mA, and evaluated the variation in the voltage. As a result, thevariation coefficients obtained by dividing the standard deviations ofthe measured voltages Vf by an average were 0.79, 4.6, 6.1, and 5.4 whenthe current If was 10, 100, 200, and 300 mA in order. The larger thevariation coefficient, the larger the variation in the voltage Vf ineach measurement. In this measurement, when the current If is 10 mA, thevariation is much smaller than other cases. In the present preferredembodiment, the current If flowing in the LED module 3 is 4.0 mA that issmaller than 10 mA, so that it can be assumed that the variation in thevoltage Vf is very small.

For example, when electric power of 7 W was supplied to 6 LED chips thenumber of which does not form a planar light source 3A unlike thepresent preferred embodiment, the temperature of the substrate 1 was 50°C. to 60° C., and on the other hand, the temperature of the substrate 1in the present preferred embodiment was 40° C. to 45° C. A possiblereason for this is that although the supplied electric power is thesame, heat radiation to the housing 5 is greater in the presentpreferred embodiment in which the LED modules 3 (LED chips 31) as heatgeneration sources are mounted in a more dispersed manner. Thus, withthe configuration including the planar light source portion 3A, heatradiation during illumination can be comparatively advantageouslyperformed.

By forming the inner surface of the reflector 4 as an uneven metalsurface, light from the lighting device A1 can be made more uniform.

FIG. 19 to FIG. 27 show another example of a lighting device andcomponents thereof according to the present invention. In thesedrawings, elements identical or similar to those in the preferredembodiment described above are provided with the same reference symbolsas in the preferred embodiment described above, and description thereofshall be omitted.

FIG. 19 shows another example of a substrate 1, a wiring pattern 2, anda plurality of LED modules 3. In the configuration shown in thisdrawing, the substrate 1 is substantially oval. The shape of the wiringpattern 2 is different from that of the preferred embodiment describedabove. The mounting density of the plurality of LED modules 3 is thesame as in the preferred embodiment described above. With thisconfiguration, the number of substrates 1 which can be formed from amaterial of the substrate 1 can be increased, and this is preferable forreduction in manufacturing cost.

FIG. 20 to FIG. 22 show another example of the LED module 3. The LEDmodule 3 shown in these drawings has a width of 0.6 mm, a length of 1.0mm, and a thickness of 0.2 mm, and is configured as a small-sized andvery thin LED module. By using this LED module 3 and setting theinterval between adjacent LED modules 3 to approximately 0.5 mm, themounting density of the LED modules 3 can be increased to at least60/cm². This configuration is suitable for making the planar lightsource portion 3A look like a light emitting surface which emits moreuniform light. This LED module 3 is equivalent to type B of the graphshown in FIG. 11. This type of LED module 3 can be expected to increaseluminous efficiency as the current IF becomes smaller. When the powerconsumption is the same as the lighting device A1, the current If can bemade smaller by increasing the mounting density.

FIG. 23 and FIG. 24 show another example of a substrate 1, a wiringpattern 2, and a plurality of LED modules 3. In the configuration shownin these drawings, the dimensions of the substrate 1 are the same as inthe examples described above; however, the configurations of the wiringpattern 2 and the LED modules 3 are different from those in thepreferred embodiments described above.

As shown in FIG. 24, this LED module 3 includes leads 35A and 35B and areflector 36. The leads 35A and 35B are plate-shaped members made of,for example, Cu—Ni alloy. On the lead 35B, an LED chip 31 is mounted,and the lead 35A is electrically conductive to the LED chip 31 via awire. The reflector 36 is made of, for example, white resin. The lowersurfaces of the leads 35A and 35B are exposed from the reflector 36, andare used as mounting terminals for surface-mounting the LED module 3.The LED module 3 has a size of 4.0 mm×2.0 mm.

As shown in FIG. 23 and FIG. 24, in the present preferred embodiment,the cathode linear portion 23B is comparatively wide. In detail, asclearly shown in FIG. 23 in a plan view, the cathode linear portion isso wide that the LED chip 31 and the cathode linear portion 23B overlapeach other. Further, the cathode linear portion 23B faces the entireback surface of the lead 35B. In the configuration using an LED module 3including an LED chip 31 installed so that its polarity is opposite tothat of the LED chip 31 of the present preferred embodiment, instead ofthe cathode linear portion 23B, the anode linear portion 23A may bewidened so as to overlap such LED chips 31.

The wiring pattern 2 includes an anode widened portion 23Aa and acathode widened portion 23Ba. The anode widened portion 23Aa iselectrically conductive to the anode linear portions 23A, and thecathode widened portion 23Ba is electrically conductive to the cathodelinear portions 23B. The anode widened portion 23Aa and the cathodewidened portion 23Ba are disposed close to end portions of the substrate1, and their outer edges are shaped along the outer edge of thesubstrate 1.

In the present preferred embodiment, the mounting density isapproximately 3.0/cm², and the occupied area ratio is approximately 24%.Even in this preferred embodiment, a planar light source portion 3Awhich can be made to look like surface luminescence as compared with aconfiguration in which, for example, 6 LED modules 3 are mounted, can beformed. Further, by setting the interval between the LED modules 3 toapproximately 0.5 mm, the occupied area ratio can be increased toapproximately 70%. This configuration is preferable for making theplanar light source portion 3A look like a light emitting surface thatemits very uniform light.

Heat from the LED chip 31 is preferably transmitted to the cathodelinear portion 23 via the lead 35B. The cathode linear portion 23Bitself is wide, so that the heat from the LED chip 31 can be quicklydiffused. Further, by the anode widened portion 23Aa and the cathodewidened portion 23Ba, radiation of heat transmitted from the anodelinear portion 23A and the cathode linear portion 23B to the outside canbe enhanced. With this configuration, in the present preferredembodiment, heat from the LED module 3 can be efficiently radiated.

FIG. 25 shows still another example of a substrate 1, a wiring pattern2, and a plurality of LED modules 3. The substrate 1 shown in thisdrawing has a contour of approximately 102 mm, and is used for alighting device A1 having a size suitable for installation in an openingwith a diameter of approximately 150 mm opened in a ceiling or the like.On this substrate 1, approximately 816 LED modules 3 of the type shownin FIG. 6 to FIG. 8 are mounted. The diameter D1 of the opening 41 ofthe reflector 4 is set to approximately 70 mm.

The wiring pattern 2 includes a plurality of nonconductive radiationportions 28. The nonconductive radiation portions 28 are notelectrically conductive to any of the anode linear portions 23A and thecathode linear portions 23B, and are disposed close to the end portionof the substrate 1 with respect to the anode linear portions 23A and thecathode linear portions 23B. Each nonconductive radiation portion 28 hasan outer edge along the outer edge of the substrate 1.

With this configuration, the planar light source portion 3A can also bemade to look like a light emitting surface. By providing thenonconductive radiation portions 28, a part of the substrate 1 can beprevented from becoming improperly high in temperature.

Of course, as in the example described above, it is also possible thatthe LED modules 3 shown in FIG. 25 are thinned out to reduce the numberof LED modules 3 to ½ of that in the configuration of FIG. 25.Accordingly, a necessary illuminance can be secured and excellentluminous efficiency can be realized by a smaller number of LED modules3.

FIG. 26 shows a lighting device according to a second preferredembodiment of the present invention. The lighting device A2 of thepresent preferred embodiment includes the housing 5 the configuration ofwhich is different from that in the preferred embodiment describedabove. The housing 5 of the present preferred embodiment has a bottomportion 51 and a cylindrical portion 52, and structured so that theseportions are linked integrally. The substrate 1 is in contact with thebottom portion 51.

With this configuration, heat can be quickly transmitted from thesubstrate 1 to the bottom portion 51. Then, this heat can be diffusedfrom the bottom portion 51 to the cylindrical portion 52. Accordingly,heat radiation performance of the plurality of LED modules 3 can befurther enhanced.

FIG. 27 shows a lighting device according to a third preferredembodiment of the present invention. The lighting device A3 in thepresent preferred embodiment is a power source separate type in which apower supply unit is disposed separately of the lighting device mainbody. Therefore, the housing 5 of the preferred embodiment describedabove is not provided. Accordingly, the lighting device main body can bereduced in height, so that it can be installed into a mounting spaceeven if the mounting space is limited.

Other detailed configurations of the respective portions of the lightingdevice can be variously changed in design.

For example, in addition to the configuration in which all LED modules 3emit light with the same wavelength, a configuration in which aplurality of LED modules 3 that emit light with wavelengths differentfrom each other is also possible. For example, a configuration includingLED modules 3 that emit incandescent light and LED modules 3 that emitdaylight color is also possible. In this case, by controllingproportions of the LED modules to be made to actually emit light amongthe incandescent-light LED modules 3 and the daylight-color LED modules3, or by individually controlling the currents If of the LED modules 3,incandescent light, warm white, white, neutral white, and daylight colorcan be arbitrarily irradiated. Further, for example, green LED modules 3may be disposed so as to surround white LED modules 3. A usage may suchthat white LED modules 3 are made to emit light normally, and in case ofemergency, green LED modules 3 are made to emit light. The LED modules 3are not limited to an LED module that includes one LED chip 31, and mayinclude three LED chips 31 which emit red light, green light, and bluelight, for example.

Without changing the configurations of the substrate 1 and the wiringpattern 2, by reducing the number of LED modules 3, the rated powers ofthe lighting device A1 to A3 can be easily changed. For example, whenLED modules 3 are omitted at a rate of one of every three from theplurality of LED modules 3 of the lighting device A1, the rated powercan be reduced to ⅔. Alternatively, when LED modules 3 are omitted at arate of two of every three from the plurality of LED modules 3 of thelighting device A1 to A3, the rated power can be reduced to ⅓.

It is also possible that a lens is provided on the exit-side opening 41side of the reflector 4 to condense or diffuse light generated from theLED modules 3.

By properly setting the color of the substrate 1 and the color of theresist covering the wiring pattern 2, a configuration in which anarbitrary pattern or character appears when the LED modules 3 are turnedoff can be realized.

The shape of the substrate 1 is not limited to a circle, but may bevarious shapes such as a rectangle typified by a square, a polygon suchas a hexagon, etc.

The use of the lighting device is not limited to a downlight, and can beused for various purposes in which light irradiation from a planar lightsource portion is preferable.

FIG. 28 to FIG. 30 show an LED lamp as a lighting device according to afourth preferred embodiment of the present invention. The LED lamp A11of the present preferred embodiment includes a substrate 101, aplurality of LED modules 103, a radiation member 111, a power supplysubstrate 104, a plurality of power supply components 105, a case 106,and a pair of caps 107, and is used as, for example, a replacement of astraight tube fluorescent lamp by being attached to a generalfluorescent lamp lighting fixture.

The substrate 101 is made of, for example, glass epoxy resin, and isformed to have a long rectangular shape. The substrate 101 is stacked onthe radiation member 111, and attached to the radiation member 111 byusing, for example, screws. As the substrate 101, an aluminum plate thesurface of which is insulated may be used.

On the upper surface 101 a of the substrate 101, a plurality of LEDmodules 103 are mounted. As shown in FIG. 30, in the present preferredembodiment, the plurality of LED modules 103 are arrayed along a planeincluding the central axis O1 of the case 106. As shown in FIG. 31, theplurality of LED modules 103 are arrayed zigzag. As shown in FIG. 32 toFIG. 34, the LED module 103 includes an LED chip 131, a resin package132, a substrate 133, and a pair of mounting terminals 134. The LEDmodule 103 has a width of 0.6 mm, a length of 1.0 mm, and a thickness of0.2 mm, and is configured as a small-sized and very thin LED module.

The substrate 133 is an insulating substrate having a substantiallyrectangular shape in a plan view and made of, for example, glass epoxyresin. On the surface of the substrate 133, the LED chip 131 is mounted.On the back surface of the substrate 133, a pair of mounting terminals134 are formed. The thickness of the substrate 133 is set toapproximately 0.05 mm to 0.08 mm. The LED chip 131 is a light source ofthe LED module 103, and can emit, for example, visible light. The resinpackage 132 is for protecting the LED chip 131. The resin package 132 ismolded by using, for example, epoxy resin having translucency for lightfrom the LED chip 131 or a translucent resin containing a fluorescentmaterial which is excited by light from the LED chip 131 to emit lightwith a different wavelength. In the present preferred embodiment, forexample, by mixing blue light from the LED chip 131 and yellow lightfrom the fluorescent material contained in the resin package 132, theLED module 103 can irradiate white. As the fluorescent material, insteadof the fluorescent material that emits yellow light, a fluorescentmaterial that emits red light and green light may also be used.

As shown in FIG. 31, on the substrate 101, a wiring pattern 102 isformed. The wiring pattern 102 is formed of a metal film of, forexample, copper, and is for mounting a plurality of LED modules 103 andsupplying electric power thereto. The wiring pattern 102 includes aplurality of pad portions 122. In the wiring pattern 102, portions otherthan the portions for mounting the LED modules 103 are covered by aninsulating layer (not shown) with high reflectance, for example, whiteresist.

The plurality of pad portions 122 are portions on which the plurality ofLED modules 103 are mounted. The pad portion 122 includes an anodelinear portion 123A (black in the drawing) and a cathode linear portion123B (gray in the drawing). The anode linear portion 123A and thecathode linear portion 123B extend in the longitudinal direction X, andare disposed parallel to each other at an interval in the widthdirection Y. Accordingly, all of the plurality of pad portions 122extend along the longitudinal direction X. Most of the plurality of padportions 122 are disposed parallel to each other at intervals in thewidth direction Y. Further, several pad portions 122 are disposed inseries at intervals in the longitudinal direction X.

The LED module 103 is mounted on the pad portion 122 by soldering one ofthe pair of mounting terminals 134 to the anode linear portion 123A andsoldering the other mounting terminal to the cathode linear portion 12B.Accordingly, a plurality of LED modules 103 mounted on one pad 122 areconnected in parallel to each other. Across the oblique joint portion125, two groups each consisting of a plurality of LED modules 103connected in parallel are disposed. The two pad portions 122 disposed onboth sides of the oblique joint portion 125 have the same disposition ofthe anode linear portion 123A and the cathode linear portion 123B in thewidth direction Y. The oblique joint portion 125 joins the anode linearportion 123A of one of the pad portions 122 and the cathode linearportion 123B of the other pad portion 122. Accordingly, the plurality ofLED modules 103 belonging to these two groups are connected in series toeach other.

With this configuration, the plurality of LED modules 103, that is, theplurality of LED chips 131 are connected as shown in FIG. 35. In thepresent preferred embodiment, the plurality of LED modules 103 aredivided into a plurality of groups 131A. The group 131A includes aplurality of LED modules 103 connected in parallel to each other. Thesegroups 131A are connected in series to each other. The series circuit ofthe plurality of groups 131A is connected to the power supply unitformed on the power supply substrate 104 (see FIG. 29). As this powersupply unit, the same constant current power supply unit as shown inFIG. 10 described above can be applied.

Although a so-called rated current of each LED module 103 (LED chip 131)is 20 mA, the actual current If flowing is, for example, not more than4.0 mA. When the plurality of LED modules 103 mounted at high densityemit light, they do not look like a set of a plurality of point lightsources to the naked eye, but look like surface luminescence.Specifically, the region in which the plurality of LED modules 103 aremounted forms a planar light source portion 103A.

In detail, when the LED lamp A11 has a size corresponding to a 40 Wstraight tube fluorescent lamp (substrate size is approximately 1.7cm×120 cm), the number of LED modules 103 to be mounted is not less than600. More preferably, the number of LED modules 103 to be mounted is notless than 1000, not less than 4000, not less than 8000, and not lessthan 12000.

When the LED lamp A11 has a size corresponding to a 20 W straight tubefluorescent lamp (substrate size is approximately 1.7 cm×58 cm), thenumber of LED modules 103 to be mounted is not less than 290. Morepreferably, the number of LED modules 103 to be mounted is not less than480, not less than 1900, not less than 3900, and not less than 5800.

When the LED lamp A11 has a size corresponding to a 15 W straight tubefluorescent lamp (substrate size is approximately 1.7 cm×44 cm), thenumber of LED modules 103 to be mounted is not less than 200. Morepreferably, the number of LED modules 103 to be mounted is not less than330, not less than 1300, not less than 2700, and not less than 4000.

When the LED lamp A11 has a size corresponding to a 10 W straight tubefluorescent lamp (substrate size is approximately 1.7 cm×33 cm), thenumber of LED modules 103 to be mounted is not less than 150. Morepreferably, the number of LED modules 103 to be mounted is not less than250, not less than 1000, not less than 2000, and not less than 3000.

For example, when the size corresponds to 40 W and the number of LEDmodules to be mounted is 12000, the interval between the LED modules 103adjacent to each other results from reduction in the distance betweenthe LED modules, and the distance is approximately 0.5 mm. When the areaof the substrate 101 (1.7 cm×120 cm: equivalent to the opening areafacing the illumination space of the planar light source portion) isconverted into the number of LED modules 103 to be mounted, the numberof LED modules to be mounted is approximately 600/cm² (12000/(1.7 cm×120cm)). When an allowance is provided for the interval between the LEDmodules 103, the number of LED modules 103 to be mounted to the area ofthe substrate 101 is approximately 5/cm². When a larger allowance isprovided for the interval between the LED modules 103, the mountingdensity of the LED modules 103 to the area of the substrate 101 isapproximately 3/cm². Therefore, the number of LED modules to be mountedto the area of the substrate 101 is preferably within the range fromapproximately 3/cm² to 60/cm². For example, the number is 5/cm², 20/cm²,and 40/cm², etc.

From the point of view of the occupation ratio of the total area of theLED modules 103 to the area of the substrate 101, the upper limit of theoccupation ratio is preferably approximately 36% (0.1 cm×0.06cm×12000/(1.7 cm×120 cm)). When the distance between LED modules is setso that the number of LED modules 103 to be mounted to the area of thesubstrate 101 becomes 3/cm², the occupation ratio of the total area ofthe LED modules 103 to the area of the substrate 101 becomesapproximately 1.8% (0.1 cm×0.06 cm×600/(1.7 cm×120 cm)). Therefore, inthis case, the occupation ratio of the total area of the LED modules 103to the area of the substrate 101 is preferably not less thanapproximately 1.8%.

The number of the plurality of LED modules 103 (the number of rows) tobe mounted in the width direction Y is at least not less than 3 rows.When the interval between the LED modules 103 adjacent to each other isset to approximately 0.5 mm, this number of rows reaches 15. Morepreferably, the mounting density, the number of LED modules 103 to bemounted per unit length, in the longitudinal direction X is larger thanthe mounting density per unit length in the width direction Y. Theoccupation ratio of the LED modules 103 in the longitudinal direction Xis preferably larger than the occupation ratio in the width direction Y.For obtaining this configuration, the longitudinal direction of the LEDmodules 103 may be set along the longitudinal direction X of thesubstrate 101.

The radiation member 111 is made of, for example, A1, and has a narrowand long block shape extending in the longitudinal direction X of thesubstrate 101 as shown in FIG. 28 and FIG. 29. As clearly shown in FIG.30, the radiation member 111 has a hollow semicircular shape in asection. In the hollow portion of the radiation member 111, the powersupply substrate 104 and a plurality of power supply components arehoused.

The power supply substrate 104 is made of, for example, glass epoxyresin, and is formed to have a long rectangular shape. The plurality ofpower supply components 105 function as a power supply circuit fordriving the LED modules 103, and are mounted on both surfaces of thepower supply substrate 104. The plurality of power supply components 105include an AC/DC converter 151 and other functional components 152 suchas capacitors and resistors, and are arranged to convert an alternatingcurrent supplied from a commercial power supply into a DC constantcurrent and supply it to the LED modules 103. The AC/DC converter 151occupies a larger space than other components mounted on the powersupply substrate 104.

The case 106 is for housing the substrate 101 and the radiation member111, and has a straight tube-like cylindrical shape having a circularsection as clearly shown in FIG. 30. On the inner surface of the case106, a pair of projecting pieces 161 projecting inward are formedintegrally. The case 106 thus configured is made of a synthetic resin,for example, polycarbonate, and is integrally formed by extrusionmolding.

In the housed state shown in FIG. 30, the substrate 101 is restrictedfrom moving in a direction (upward direction in the drawing)perpendicular to the central axis O1 with respect to the case 106 bycontact of the upper surface 101 a with the projecting pieces 161. Thesubstrate 101, the radiation member 111, and the power supply substrate104 are housed into the case 106 by inserting the substrate 101 and theradiation member 111 into the case 106 while sliding these below theprojecting pieces 161.

The pair of caps 107 are for supplying electric power from a commercialAC power supply by being fitted to a socket of a fluorescent lamplighting fixture. As shown in FIG. 29, the cap 107 includes a bottomedcylindrical cover body 171, a resin block 172 housed and held in thehollow portion of the cover body 171, and two terminals 173. Theradiation member 111 is supported by the pair of caps 107. The terminals173 and the power supply substrate 104 are connected by electric wires.The terminals 173 are provided to penetrate through the cover body 171and the resin block 172. One end portions (outer end portions) of theterminals 173 are portions to be fitted to slots of the socket of thefluorescent lamp lighting fixture, and the other end portions of theterminals 173 are electrically conductive between the substrate 101 andthe wiring 102.

Next, operations of the LED lamp A11 will be described.

According to the present preferred embodiment, light is emitted from theplanar light source portion 103A constituted by the plurality of LEDmodules 103. For example, when light emitted from a plurality of pointlight sources is observed, different from the case where a plurality ofsharp and bright luminescent spots are observed, light from the planarlight source portion 103A is light with entirely uniform luminance.Therefore, without providing the case 106 with a strong diffusionfunction, uniform light can be emitted from the LED lamp A11. This issuitable for reducing light attenuation due to the case 106, and theluminous efficiency of the LED lamp A11 can be increased.

In order to properly emit planar light with uniform luminance from theplanar light source portion 103A, the number of LED modules 103 to bemounted is set to the above-described number, density, or occupationratio. Array of the LED modules 103 more densely in the longitudinaldirection X than in the width direction Y is suitable for preventinglight from the LED lamp A11 formed as a straight tube from lookingnonuniform in the longitudinal direction X.

As the level of the current If flowing in the LED module 103 (LED chip131), a value not more than 4.0 mA is comparatively low. In the case ofthe LED module 103 with specifications to be used in the presentpreferred embodiment, as the current If becomes smaller, the ratio to beconsumed for heat generation in the supplied electric power can be madesmaller. Specifically, as in the case of the first preferred embodimentdescribed above, when the LED module 103 is driven with a current notmore than 8 mA (more preferably, not more than 4 mA), excellent luminousefficiency is obtained. In other words, when the LED module 103 (LEDchip 131) is driven with a current of not more than 20% (morepreferably, not more than 40%) of the rated current, excellent luminousefficiency is obtained. For improving the illuminance unevenness,driving of the LED module 103 with a current not more than 8 mA (40% ofthe rated current) (more preferably, not more than 4 mA (20% of therated current) is preferable.

It was also found through the inventors' research that reduction in thecurrent If to be supplied to each LED module 103 is advantageous forreducing the variation in the voltage Vf for setting the current If to adesired level. The inventors measured the voltage Vf for the pluralityof LED modules 103 when the current If was regulated to 10, 100, 200,and 300 mA, and evaluates the variation. As a result, the variationcoefficients obtained by dividing the standard deviations of themeasured voltages Vf by an average were 0.79, 4.6, 6.1, and 5.4 when thecurrent If was 10, 100, 200, and 300 mA in order. The larger thevariation coefficient, the larger the variation in the voltage Vf ineach measurement. In this measurement, when the current If is 10 mA, thevariation is much smaller than other cases. In the present preferredembodiment, the current If flowing in the LED module 103 is 4.0 mA thatis smaller than 10 mA, so that it can be assumed that the variation inthe voltage Vf is very small.

By providing the oblique joint portion 125, the plurality of LED modules103 arrayed systematically in the longitudinal direction X can beconnected so as to belong to a plurality of groups connected in seriesto each other. The systematic array of the plurality of LED modules 103is important for obtaining uniform surface luminescence. Connection ofthe plurality of LED modules 103 so as to belong to the plurality ofgroups connected in series to each other is advantageous for setting thecurrent If to be supplied to each LED modules 103 to a low currentsuitable for high-efficiency luminescence and setting the voltagebetween the anode electrode 121A and the cathode electrode 121B toapproximately 27V that realizes comparatively easy constant currentcontrol.

For example, unlike the present preferred embodiment, when electricpowers for emitting luminances equivalent to each other were supplied toLED chips the number of which does not constitute the planar lightsource portion 103A, the temperature of the substrate was 50° C. to 60°C., and on the other hand, in the present preferred embodiment, thetemperature of the substrate 101 was 40° C. to 45° C. The possiblereason for this is that although the supplied powers are equal to eachother, heat radiation is enhanced more in the present preferredembodiment in which LED chips 131 as heat generation sources are mountedin a more dispersed manner. With this configuration including the planarlight source portion 103A, heat radiation during illumination can becomparatively advantageously performed.

As described above, inside the case 106, paired projecting pieces 161are provided, and according to contact of these projecting pieces 161with the upper surface 101 a on both ends in the width direction Y ofthe substrate 101, the substrate is restricted from moving in adirection (radial direction of the case 106) perpendicular to thecentral axis O1 of the case 106 with respect to the case 106.Accordingly, when assembling the LED lamp A11, only by inserting thesubstrate 101 into the case 106, the substrate 101 can be positionedrelative to the case 106. Therefore, the LED lamp A11 can be easilyassembled.

FIG. 36 shows an exemplary variation of the array and configuration ofthe LED modules 103 in the LED lamp A11. In this exemplary variation,most of the plurality of modules 103 are LED modules that emit whitelight, and in addition, a small number of LED modules 103 r areconfigured as LED modules that emit red light. The LED modules 103 r arearrayed discretely while sandwiching a predetermined number of LEDmodules 103 that emit white light. With this configuration, light morecolorful than white light which is obtained by mixing only blue lightand yellow light, that is, light with higher color effect can beemitted.

FIG. 37 to FIG. 39 show an exemplary variation of an LED module 103 tobe used in the LED lamp A11. In this exemplary variation, the LED module103 has a size of 1.6 mm×0.8 mm in a plan view and a height ofapproximately 0.55 mm. In this case, when the interval between the LEDmodules 103 adjacent to each other is set to 0.5 mm, the occupationratio of the total area of the LED modules 103 to the area of thesubstrate 101 can be increased to approximately 47%.

FIG. 40 to FIG. 42 show another exemplary variation of an LED modules103 to be used in the LED lamp A11. In this exemplary variation, the LEDmodule 103 includes a case 135. The case 135 is made of, for example,white resin, and has a reflecting surface 135 a surrounding the LED chip131 and the resin package 132. The reflecting surface 135 a is fordirecting light advancing sideward from the LED chip 131 upward.Therefore, this LED module 103 belongs to a comparatively high-luminancetype. The LED module 103 has a size of 4.0 mm×2.0 mm in a plan view anda height of approximately 0.55 mm. In this case, by setting the intervalbetween the LED modules 103 adjacent to each other to 0.5 mm, theoccupation ratio of the total area of the LED modules 103 to the area ofthe substrate 101 can be increased to approximately 70%.

FIG. 43 and FIG. 44 show an LED lamp according to a fifth preferredembodiment of the present invention. In these drawings, elementsidentical or similar to those in the fourth preferred embodimentdescribed above are provided with the same reference symbols as in thepreferred embodiment described above. In the LED lamp A12 of the presentpreferred embodiment, the configurations of the substrate 101 and theradiation member 111 are different from those of the fourth preferredembodiment described above.

In the present preferred embodiment, as the substrate 101, a flexiblewiring substrate made of a comparatively thin resin layer (not shown)and a metal wiring layer (not shown) is used. This substrate 101 hashigh flexibility, and is wound around a radiation member 111 having acylindrical shape. Therefore, the width direction y of the substrate 101is the circumferential direction of the radiation member 111 in thepresent preferred embodiment.

The metal wiring layer of the substrate 101 has a configuration similarto that of the wiring pattern 102 of the preferred embodiment describedabove, and a plurality of LED modules 103 are mounted thereon. Theplurality of LED modules 103 are arrayed zigzag at a high density.

According to this preferred embodiment, the luminous efficiency of theLED lamp A12 can also be increased. The LED lamp A12 has a form in whichthe entire surface of the cylinder emits light according to luminescenceof the plurality of LED modules 103. Therefore, the diffusion functionby the case 106 can be further weakened. This leads to an increase intransmittance of the case 106, and is advantageous for increasing theluminous efficiency of the LED lamp A12.

Further, the area of the substrate 101 on which the LED modules 103 canbe mounted can be dramatically increased, and this is preferable forincreasing the number of LED modules 103 to be mounted. In detail, thenumber of LED modules 103 to be mounted can be increased toapproximately 9400 when the LED lamp A12 is equivalent to a 10 W lamp,approximately 12500 when the LED lamp A12 is equivalent to a 15 W lamp,approximately 18000 when the LED lamp A12 is equivalent to a 20 W lamp,and approximately 37000 when the LED lamp A12 is equivalent to a 40 Wlamp.

FIG. 45 to FIG. 47 show an LED lamp according to a preferred sixthembodiment of the present invention. The LED lamp A13 of the presentpreferred embodiment has a configuration of the radiation member 111 anda disposition of a plurality of electronic components 105 different fromthose in the preferred embodiment described above.

In the present preferred embodiment, as clearly shown in FIG. 47, aplurality of recess portions 111 a are formed on the surface of theradiation member 111 so that the surface has unevenness. The recessportions 111 a are formed over the entire length of the radiation member111 along the longitudinal direction x of the substrate 101.

The power supply substrate 104 is attached to the substrate 101 by aplurality of metal leads 141. One end portions of the plurality of leads141 are fixed to both end portions in the longitudinal direction of thepower supply substrate 104 by soldering, and the other end portions aresoldered on a pad not shown provided on the upper surface 101 a of thesubstrate 101. Accordingly, the power supply substrate 104 is spacedfrom the substrate 101 or the radiation member 111. The wiring of thesubstrate 101 and the wiring of the power supply substrate 104 are madeelectrically conductive to each other via the leads 141.

In the case 106, the projecting pieces 161 are biased to the lower side(in the radial direction) from the central axis O1 of the case 106,project within a plane parallel to the central axis O1, and extend in adirection along the central axis O1. The substrate 101 is at a positionbiased to the side opposite to the upper surface 101 a from the centralaxis O1 of the case 106, and the power supply substrate 104 ispositioned near the central axis O1 of the case 106. Thus, the powersupply substrate 104 is positioned closer to the central axis O1 thanthe substrate 101, so that the width of the power supply substrate 104can be made larger than the width of the substrate 101. The substrate101, the radiation member 111, and the power supply substrate 104 arehoused into the case 106 by inserting the substrate 101 and theradiation member 111 into the case 106 while sliding below theprojecting pieces 161.

The cap 107 includes a bottomed cylindrical cover body 171, a resinblock 172 housed and held in the hollow portion of the cover body 171,and two terminals 173. On the resin block 172, a recess portion 172 a isformed, and by inserting and fitting the end portion in the longitudinaldirection X of the radiation member 111 into the recess portion 172 a,the cap 107 is attached to the radiation member 111. Accordingly, in theLED lamp A13, the radiation member 111 is supported by the pair of caps107.

A partially cylindrical gap is provided between the cover body 171 andthe resin block 172, and in a state where the cap 107 is attached to theradiation member 111, both end portions in the longitudinal direction Xof the case 106 are inserted in the gap. Here, as clearly shown in FIG.19, between a tip end edge 106 a in the longitudinal direction X of thecase 106 and an end edge 172 b of the resin block 172, a gap isprovided.

With this configuration, a comparatively large-sized AC/DC converter 151can be properly disposed inside the case 106. Even if the case 106thermally expands, it can be prevented from interfering with the cap107.

An LED lamp according to the present invention is not limited to theabove-described preferred embodiments. Detailed configurations of thecomponents of the LED lamps according to the present invention can bevariously changed in design.

Other than the configuration in which all LED modules 103 emit lightwith the same wavelength, a configuration including a plurality of LEDmodules 103 that emit light with wavelengths different from each otheris also possible. For example, a configuration including LED modules 103that emit incandescent light and LED modules 103 that emit daylightcolor is also possible. In this case, by controlling the proportions ofLED modules 103 that are made to emit light among the incandescent-lightLED modules 103 and the daylight-color LED modules 103, or byindividually controlling the levels of the currents If of the LEDmodules 103, incandescent light, warm white, white, neutral white, anddaylight color can be arbitrarily irradiated. The LED module 103 is notlimited to an LED module including one LED chip 131, and may include,for example, three LED chips 131 that emit red light, green light, andblue light.

Preferred embodiments of the present invention are described in detailabove; however, these are just the detailed examples used for clarifyingthe technical contents of the present invention, and the presentinvention should not be interpreted as being limited to detailedexamples, and the spirit and scope of the present invention shall belimited only by the accompanying claims.

DESCRIPTION OF REFERENCE SYMBOLS

A1, A2, A3: a lighting device, D1: (substrate-side opening) diameter,D2: (exist-side opening) diameter, x: (second) direction, y: (first)direction, H: distance, 1: substrate, 2: wiring pattern, 3: LED module,3A: planar light source portion, 4: reflector, 5: housing, 6: connector,7: holder, 8: support substrate, 9: columnar support, 21A: anodeelectrode, 21B: cathode electrode, 22: pad portion, 23A: anode linearportion, 23B: cathode linear portion, 23Aa: anode widened portion, 23Ba:cathode widened portion, 24A: anode folding portion, 24B: cathodefolding portion, 25: oblique joint portion, 26: straight joint portion,27A: anode connecting portion, 27B: cathode connecting portion, 28:nonconductive radiation portion, 31: LED chip, 31A: group, 32: resinpackage, 33: substrate, 34: mounting terminal, 41: (substrate side)opening, 42: (exit side) opening, 51: bottom portion, 52: cylindricalportion, 60: power supply unit, 60A: power supply substrate, 61: surgeprotection circuit, 62: filter circuit, 63: rectifying circuit, 64:control circuit, 65: reverse voltage protection circuit, 66: commercialAC power supply, 67, 68: power feeder, 69: fuse, 70: varistor, 71:inductor, 72, 73: capacitor, 74: diode, 75: constant current driver, 75a, 75 b: power supply terminal, 75 c: control terminal, 75 d, 75 e:output terminal, 76 to 78: smoothing capacitor, 79: current settingresistor element, 80, 81: DC power feeder, 82, 83: output terminal, 84,85: output line, 86, 87: lead wire, A11, A12, A13: LED lamp, 101:substrate, 101 a: upper surface, 102: wiring pattern, 103, 103 r: LEDmodule, 103A: planar light source portion, 104: power supply substrate,104 a: upper surface, 104 b: lower surface, 105: power supply component,106: case, 107: cap, 111: radiation member, 122: pad portion, 123A:anode linear portion, 123B: cathode linear portion, 125: oblique jointportion, 131: LED chip, 131A: group, 132: resin package, 133: substrate,134: mounting terminal, 151: AC/DC converter, 161: projecting piece,171: cover body, 172: resin block, 173: terminal

What is claimed is:
 1. A lighting device, comprising: a substrate havinga side extending straight in a first direction; a first LED chipsupported on the substrate, and having a first anode terminal and afirst cathode terminal; a second LED chip supported on the substratespaced from the first LED chip, and having a second anode terminal and asecond cathode terminal; a third LED chip supported on the substratespaced from the first and second LED chips, having a third anodeterminal and a third cathode terminal, being electrically connected tothe second cathode terminal, and being overlapped with the first LEDchip when viewed in a second direction that is perpendicular to thefirst direction; and a wiring connecting the first cathode terminal andthe second anode terminal with each other, at least a portion of thewiring angled at an acute angle with respect to the second direction. 2.The lighting device according to claim 1, further comprising a fourthLED chip supported on the substrate, electrically connected to the firstanode terminal of the first LED chip, and being overlapped with thefirst LED chip and the third LED chip when viewed in the seconddirection.
 3. The lighting device according to claim 2, furthercomprising a fifth LED chip supported on the substrate, electricallyconnected to the third cathode terminal of the third LED chip, and beingoverlapped with the first LED chip, the third LED chip and the fourthLED chip when viewed in the second direction.
 4. The lighting deviceaccording to claim 1, further comprising a fifth LED chip supported onthe substrate, electrically connected to the third cathode terminal ofthe third LED chip, and being overlapped with the first LED chip and thethird LED chip when viewed in the second direction.
 5. The lightingdevice according to claim 1, wherein a plurality of LED chips includingthe first LED chip, the second LED chip and the third LED chip aresupported on the substrate, and are disposed in a first array, theplurality of the LED chips in the first array includes a first end LEDchip located at an extreme end of the first array and a second end LEDchip located at an opposite extreme end of the first array in the seconddirection, and the first, second, and third LED chips are locatedbetween the first end LED chip and the second end LED chip in the seconddirection.
 6. The lighting device according to claim 5, furthercomprising: an anode electrode supported on the substrate, the first endLED chip of the first array being electrically connected to the anodeelectrode; and a cathode electrode supported on the substrate, thesecond end LED chip of the first array being electrically connected tothe cathode electrode.
 7. The lighting device according to claim 1,further comprising a plurality of further LED chips that are supportedon the substrate and that are disposed in a second array extending alongthe second direction.
 8. The lighting device according to claim 7,further comprising a plurality of further LED chips that are supportedon the substrate and that are disposed in a third array extending inparallel with the second array.
 9. The lighting device according toclaim 7, wherein each of the first LED chip and the third LED chip isspaced from the second array in the first direction.
 10. The lightingdevice according to claim 7, wherein each of the first LED chip, thesecond LED chip and the third LED chip is spaced from the second arrayin the first direction.
 11. The lighting device according to claim 7,wherein the plurality of the LED chips in the second array includes athird end LED chip located at an end of the second array, and thelighting device further comprises an anode electrode supported on thesubstrate, the third end LED chip of the second array being electricallyconnected to the anode electrode.
 12. The lighting device according toclaim 7, wherein the plurality of the LED chips in the second arrayincludes a fourth end LED chip located at an end of the second array,and the lighting device further comprises a cathode electrode supportedon the substrate, the fourth end LED chip of the second array beingelectrically connected to the cathode electrode.
 13. The lighting deviceaccording to claim 7, wherein the plurality of the LED chips in thesecond array includes a third end LED chip and a fourth end LED chiplocated at both ends of the second array, respectively, the lightingdevice further comprises an anode electrode supported on the substrate,and a cathode electrode supported on the substrate, the third end LEDchip of the second array is electrically connected to the anodeelectrode, and the fourth end LED chip of the second array iselectrically connected to the cathode electrode.
 14. The lighting deviceaccording to claim 8, wherein the plurality of the LED chips in thethird array includes a fifth end LED chip located at an end of the thirdarray, and the lighting device further comprises an anode electrodesupported on the substrate, the fifth end LED chip of the third arraybeing electrically connected to the anode electrode.
 15. The lightingdevice according to claim 8, wherein the plurality of the LED chips inthe third array includes a sixth end LED chip located at an end of thethird array, and the lighting device further comprises a cathodeelectrode supported on the substrate, the sixth end LED chip of thethird array being electrically connected to the cathode electrode. 16.The lighting device according to claim 8, wherein the plurality of theLED chips in the third array includes a fifth end LED chip and a sixthend LED chip located at both ends of the third array, respectively, thelighting device further comprises an anode electrode supported on thesubstrate, and a cathode electrode supported on the substrate, the fifthend LED chip of the third array is electrically connected to the anodeelectrode, and the sixth end LED chip of the third array is electricallyconnected to the cathode electrode.
 17. The lighting device according toclaim 1, wherein the substrate includes a second side parallel to theside, and a plurality of LED chips including the first, second and thirdLED chips is disposed between a first arc-shaped wiring extending fromthe side toward the second side, and a second are-shaped wiringextending from the side toward the second side.